Apparatus for bending sheet glass



Sept. 3, 1940. o. H. PADDQCK ET AL.

APPARATUS FOR BENDING SHEET.GLAS$ Filed Sept. 29, 1938 Snnentora OEMOND H. PADDOCK. AAT'HUR M K. GFEAVEJTWHLKEE attorney Patented Sept. 3, 1940 UNITED STATES APPARATUS FOR BENDING SHEET GLASS Ormond-H. Paddock and Arthur McK. Greaves- Walker, ioledo, Ohio, assignors to Libbey- Owens-Ford Glass Company, Toledo, Ohio, a

corporation of Ohio Application September 29, 1938, Serial No. 232,368

3 Claims.

The present invention relates to apparatus for bending glass sheets or plates.

It has been customary in the bending of glass sheets or plates to make use of so-called sand molds made of a powdered material which will not fuse when subjected to excessive heat and the upper surface of which is given a concave curvature corresponding to the curvature to which the sheet or plate isto be bent. Sand molds possess numerous advantages over the ordinary iron mold and among which may be mentioned the fact that the curvature of the sand mold may be readily varied so that it is not necessary to provide a separate mold for each curvature desired. I I

Heretofore, it has been the usual practice'to build up the sand molds upon the floor of the bending furnace but this method is objectionable in that considerable time is lost in waiting for the furnace to cool down after each bending operation to permit the removal of the bent sheets and the subsequent heating up of the furnaceto bending temperature. Consequently, upon the bending of each sheet or series of sheets the furnace must undergo a heating-up and cooling-down cycle. Likewise, it is necessary to permit the cooling down of the furnace whenever it is desired to vary the curvature of the molds.

An aim of this invention is'to provide apparatus which will embody all of the advantages incident to the use of Sand molds and at thesame time eliminate the necessity for alternate heating and cooling of the bending furnace, thereby greatly increasing the productive capacity of the furnace while simultaneously reducing costs.

An important object of the invention is theprovision of portable sand molds carriedupon movable cars or trucks whereby the said molds may be formed exteriorly of the bending furnace and then passed through the said furnace in either a continuous or intermittent manner.

Another important object of .the invention is the provision of an improved form of sand mold made from a composition of powdered refractory clay materials.

Other objects and advantages of the invention will become more apparent during the course of the following description, when taken in connection with the accompanying drawing. 1

In the drawing, wherein like numerals are employed to designate like parts throughout the same:

Fig. 1 is a vertical longitudinal sectional view through a continuous 'type of bending furnace with which are associated the improved molds provided by the invention;

Fig. 2 is a vertical transverse section through the furnace and molds taken substantially on line 2-2 of Fig. 1; and

Fig. 3 is a vertical longitudinal sectional view through another type of furnacewith which-the improved molds provided by the invention may be used.

With reference particularly to Figs. 1 and 2, the continuous bending furnace or oven illustrated is of tunnel-like formation and of any desired length, said furnace comprising opposite side walls 5 and 6 and a crown 1 cooperating to form a' substantially closed tunnel chamber 8 through which the cars or trucks 9 carrying the molds and glass sheets to be bent can be passed in a substantially straight path, ,the opposite ends of the tunnel chamber 8 being closed by vertically adjustable doors Wand: ll.

Arranged within the tunnel chamber 8 andextending longitudinally thereof are the spaced, parallel partition walls 12 and I3, defining therebetween a passageway for the cars or trucks- 9 carrying the molds and glass. The partition walls l2 and I3 are spaced inwardly of the side walls 5 and 6 respectively of the furnace and cooperate therewith to provide relatively narrow channels into which the gas flames for heating the furnace are adapted to be directed, the said channels communicating with the vault above the trucks 9 by passageways formed between the crown and the tops of the partition walls l2 and I3. The heating flames are adapted to be introduced into the channels from a plurality of burners l4 arranged along each side of the furnace and operating through openings H5 in the side walls 5 and 6. The partition walls l2 and I3 therefore serve to protect the trucks 9 from the direct action of the heating flames. It is of course to be understood that the invention is notlimited to the particular type of heating means herein disclosed.

Each of the trucks 9 is'mounted upon wheels l6 rolling along upon rails H which extendlongltudinally through the furnace. Carried upon the bottom ll! of the truck is a preferably metallic receptacle l9 within which is formed the sand mold 20, the upper surface 2| of said mold being concavely curved to correspond to the curvature to which the glass sheet 22 is to be bent. ,The flat sheet of glass 22, illustrated in broken lines in Fig. 2, is laid horizontally upon the top of the mold and. as the said mold and sheet are carried through the furnace, the glass will be subjected to a bending temperature suficient to cause the sheet to sag or sink downwardly into the mold by its own weight so that the curvature of the mold will be accurately imparted to the sheet. This softening and settling down of the sheet into the mold will cause the said sheet to be said sheet may be removed from the mold.

With the arrangement above described, the

' sand molds 20 can be lformed upon the trucks exteriorly of the furnace in the customary manner such as by moving a template of the desired curvature back and forth over the powdered material until the desired curvature is' obtained. when the mold hasbeen properly formed, the glass sheet 22 to be bent is laid thereon and the truck then passed through the furnace. This may be effected in any desired manner such as by means of an endless drive chain 23 supported in achannel 24 and engaging depending lugs 25 formed on the bottom of the trucks. By shaping the molds outside the furnace, considerable time is saved and, in addition, it is not necessary for the furnace to be alternately heated and cooled for each bending operation such as is the case when the sand molds are formed directly upon the floor of the furnace.

As pointed out above, the use of sand molds is of decided advantage over iron molds for many types of bends. However, to make a satisfactory sand mold, the bending sand must pack easily and solidly; cut smoothly and sharply; resist crumbling under glass weight load; and not be sharp or hard enough to scratch the glass.

While the mold 2!! herein provided is termed a sand mold, yet the material used for the mold is not actually 'a. special sand but instead consists of a novel and improved composition of burnt fire clay ground to the desired fineness. More specifically, the mold material consists of a mixture of tuile and common red brick ground together. The word tuile, as here used, refers to the clay doors of glass melting pot furnaces and these doors are taken after they have been used for their full life on the furnace and ground with common red brick preferably made from.alluvial clay.

Although the invention is not limited to the use of these materials in any exact proportions, it has been found in actual practice that a satisfactory mold material can be produced by using fron r80 to 90 percent of tuile with 10 to 20 percent of red brick. In fact, a large amount of bending sand ,has been made by mixing 15% of red brick with 85 of old tuile, and also by grinding 17.12% of brick with 82.88% of tuile.

In Fig. 3 is illustrated a different type of bending furnace wherein a pair of wheeled trucks carrying molds are adapted to be moved back and} forth in shuttle-like fashion. [The furnace is designated 25 and may be heated in the same manner as described above, the ends of said furnace being closed by the vertically movable doors 21 and 28. The numerals 29 and 30 designate two wheeled trucks similar to trucks 9 and connected together by a suitable coupling means 3|. During the time one truck,- for example truck 29, is disposed in the furnace, the truck 30 is arranged exteriorly thereof, while during the bending and annealing of the sheet on truck 30, another sheet to be bent can be properly positioned upon truck 29.

When the sheet upon truck 29 has been properly bent and annealed, the said truck can be moved to the right outwardly of the furnace, as

indicated by the broken lines, which will bring the truck 30 within the furnace and during the bending and annealing of the sheet on truck 30 the previously bent sheet can be removed from truck 29 and another sheet to be bent positioned thereupon. When the sheet upon truck 3|] has been properly bent and annealed, the trucks are moved to the left to again bring truck 30 exteriorly of the furnace and truck 29 within the furnace. Thus, it will be seen that the two trucks are moved back and forth like a shuttle and that during the bending and annealing of the sheet upon either truck, the bent sheet upon the other truck can be removed and the said truck reloaded. The molds carried by the trucks 29 and 30 are preferably of the same type described hereinabove.

It is to be understood that the form of the invention herewith shown and described is to be taken as the preferred embodiment of the same, and that various changes in the shape, size and arrangement of parts may be resorted to with out departing from the spirit of the invention or the scope of the subjoined claims.

We claim:

1. A glass bending mold, consisting of a bed of powdered material comprising a mixtureineluding ground tuile and commonred brick.

2. A glass bending mold, consisting of a bed of powdered material including from. 80% to 90% ground old tuile mixed with from 10% to 20% ground common red brick.

3. A glass bending mold consisting of a bed of powdered material comprising a mixture of ground burnt fire clay and common red brick made from an alluvial clay.

ORMOND H. PADDOCK. ARTHUR McK. GREAVES-WALER. 

